The invention relates to an apparatus for interrupting the operation of a movable closing member, such a vehicle sun roof, upon encountering an obstacle.
German patent document DE 42 01 019 C2 has disclosed an apparatus of the generic type in which a pressure-sensitive sensor strip is arranged on the stationary closing edge of the opening that can be closed off by the closing member (sliding sunroof). In this way, it is possible in principle to detect obstacles in a highly sensitive manner. Such detection is superior to obstacle identification based on the monitoring of the load current of the electric drive, since the sensor strip responds even in the event of a low pressure load. Such an apparatus is intended to prevent an object, for example a finger, being caught during a closing operation, between the closing edge of the moved closing member and the stationary closing edge at the opening edge. The implementation of the sensor strip by means of a resistive foil pressure sensor is recommended in this publication, for reasons of cost and mechanical reliability. The arrangement of the sensor strip on the stationary closing edge is initially recommended on account of the simple conductor routing and the functional reliability associated therewith.
However, in the case of the known apparatus, the response of the sensor strip arranged on the stationary closing edge can be impaired by covering and guiding parts on the frame or, for example in the case of the sliding sunroof, by the automatically erected draught deflector. This may give rise to the sensor technology failing to identify, in the same way and in good time, the state in which an object is caught for all situations and obstacles.
A further disadvantage of a sensor strip arranged on the stationary closing edge is the late identification of an obstacle which initially impedes only of the moved closing part.
German patent document DE 88 14 544 U1 further discloses a safeguarding apparatus for motor-actuated doors/gates in which, when a sensor strip arranged on the moved closing edge of the door/gate is touched by an obstacle, it emits a control signal for the deactivation of the door/gate drive. The control signal is transmitted to the stationary drive side of the door/gate by a battery-driven radio transmitter.
The object of the present invention is to develop an apparatus of the generic type which can reliably and rapidly identify an obstacle in the way of the closing operation, has a sturdy structure and can suitably switch off or reverse operation of the closing member, in good time.
This object is achieved according to the invention, in which the sensor strip is arranged along the closing edge of the closing member, and the sensor signal is transmitted to a detector unit by attenuation modulation of an alternating electromagnetic field, by means of a transponder. This arrangement has the advantage that the identification of an obstacle in the way of the closing movement is functionally separate from covering and guiding functions on the stationary closing edge. It is thus suitable for a range of motor-moved closing parts in motor vehicles. Such closing parts are, for example, sliding sunroofs, lowerable windows, tailgates, boot lids and door-closing devices.
An additional advantage of the invention is that an obstacle in the way of the closing movement is detected immediately when it first touches the closing part. Therefore, the closing operation is terminated even before an obstacle is caught as a result of its being supported against the stationary closing edge. The arrangement of the sensor strip on the moved closing edge has the further advantage that, when confronted with the risk of an object being caught, the intuitive attempt to stop the closing movement by exerting a counterforce on the moved closing edge achieves the desired effect, namely the interruption of the closing operation.
In a further advantageous embodiment, after the sensor causes the sliding sunroof to stop when it contacts an obstacle, the drive is reversed only when the pressure applied to the sensor strip exceeds a specific threshold after the sliding sunroof has been halted.
The wireless transmission of the sensor signal from the moved closing member to the electronic control device for the drive of the closing member by means of electromagnetic (also inductive or transformer) coupling has the advantage that costly signal line routing, which is susceptible to interference, by means of sliding action contacts or lines laid in loops, (which must be held tight by springs), is no longer necessary. Furthermore, in order to dispense with a supply line for operating a sensor-side transmitter, a sensor-side, independent power supply, (for example, a battery), can be provided. Far more advantageous is the inventive use of the transponder principle, in which a supply line, or a sensor-side independent power, supply for providing the transmitting power, is unnecessary.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.